A discussion about Rastan

[Tsak]

Originally Posted by chb

If you place sprites behind your foreground, everything having color 0 is transparent and shows the sprites. Hence, you cannot use that color.

Oh, right that would be the case for background sprites indeed. I stand corrected. However it should be mentioned you can still use this color normally at screen positions not intersecting with BG sprites. F.e. in the above pic we use color 0 for the pavement area, which is below the horizon (and below the back parallax building sprites).
Depending on how the game scrolls and background sprites positioning though that may not be plausible.

Originally Posted by jayminer

But other than that, I don't think memory should be an issue if the game is allowed to load between levels. There are about 5-6 different enemies on the first level of various size but often only half of them are animated, like the legs only.

That would be a great way to go about it. I'd crop enemies to 3 parts personally. Legs, upper-body and weapon. Making the weapon a different part would cut the size of many characters also and save extra ram. Not to mention the hero already swaps weapons, so that would save a lot from him as well

[roondar]

Originally Posted by chb

Depends on the sprite color depth and screen width. When using 16 color sprites, there are probably no free slots for the copper left - at least that's the case with Risky Woods, the only game I know of with such a setup. Having only 4-color sprites should give the copper enough time to do some color changes.

Furthermore, a 16 color bg will not leave any memory bandwidth to blitter or CPU in the display area, so performance takes a hit.

Yup, doing attached Sprites for a background takes up pretty much all of the DMA slots available for a scanline during the bitplane display. Not to mention this equally eats into Blitter/CPU cycles available per frame. It's not a cheap effect and probably why Risky Woods only uses a 176 pixel tall screen.

Like you, I'd say that using a 4 colour background is probably the better choice

[roondar]

Originally Posted by Tsak

I doubt anything like that will be needed. Metro Siege f.e. does more than 60 blits for character and enemy parts alone (with no frame loss), while keeping 6 of them on screen.

Doing 60 blits without losing performance is actually quite impressive and likely means alpine thought about optimising blitting a bit (and implemented that succesfully ). Most Blitting routines I've seen easily take around 400-600 CPU cycles per cookie cut blit+restore blit when all's said and done. That's on the order of 17-25% of a frame just setting up blits if you're doing 60 of them.

Not nothing, so as I said, impressive stuff

[Tsak]

Originally Posted by roondar

Doing 60 blits without losing performance is actually quite impressive and likely means alpine thought about optimising blitting a bit (and implemented that succesfully ). Most Blitting routines I've seen easily take around 400-600 CPU cycles per cookie cut blit+restore blit when all's said and done. That's on the order of 17-25% of a frame just setting up blits if you're doing 60 of them.

Not nothing, so as I said, impressive stuff

Right
Comperatively speaking (and since we're talking about plausability), Rastan with 3-part enemies, will probably need something in the ballpark of 15-20 blits for 5-6 characters on screen (plus extras). Which is roughly 1/3 of what MS blits.